Placing hippocampal single-unit studies in a historical context.

A profound increase in the study of the role of the hippocampus in behavior and cognitive processing resulted from the startling discovery by O'Keefe and Dostrovsky in 1971 that hippocampal neurons fire selectively in different regions or "place fields" of an environment. That discovery spawned a comprehensive theory of hippocampal function that was elucidated in the publication, The Hippocampus as a Cognitive Map by O'Keefe and Nadel in 1978. According to the theory, the hippocampus serves as the neural substrate for maps of allocentric space. The goal of this paper is to revisit the historical background for the development of the cognitive map theory and to examine the context in which the theory and the phenomenon of place field activity began to gain acceptance by the scientific community. While subsequent research has led some to question if the theory can adequately account for all consequences of hippocampal lesions and all the correlates of hippocampal cellular activity, it is clear the theory has stood the test of time and has been successful in generating an enormous amount of fruitful research.